There has been a growing interest in improving air quality within livestock buildings.
However, the influence of housing and management factors on air exchange rates and
indoor gas concentrations is not well understood. The aim of this study was to determine
the effects of housing and management factors on the concentrations of carbon dioxide
(CO2) and air exchange rates in 160 representative Australian pig buildings. CO2 concentrations
were measured, air changes per hour (ACH) were estimated using a CO2 balance
method, and structural and management parameters were recorded. The mean CO2
concentration measured was 858 ppm and a mean air exchange rate of 22.8 ACH was
estimated. The analysis showed that CO2 concentrations were affected by the type of
building, season, control of the wall and ridge vents, ceiling height, size of the wall vents
and height of the ridge vents. Weaner buildings had the highest CO2 concentrations while
deep-bedding shelters had the lowest. Winter CO2 concentrations were higher in all
buildings compared to summer. Buildings with automated ridge ventilation control had the
lowest CO2 concentrations. The wall ventilation inlet height was negatively correlated with
CO2 concentration. Air exchange rates were primarily affected by the type of ventilation,
inlet height, stocking density, and building width and height. In conclusion, the equable
Australian climate has allowed the construction of cheaper pig buildings, which provide an
adequate environment for pig production, although these buildings may not always
provide an optimal environment for pig production